We Owe Our Lives to Some Bugs that Ate the Sun

 

 

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The geranium is a Bette Midler sort, with a blowsy inflorescence of clustered pink blossoms tinged with pale orange. Irrepressible, she has stayed in full bloom since we brought her home more than a year ago. The New Guinea impatiens is just the opposite, a Maria Callas diva haughty about her ability to outlast the sun. Taken offstage and carried to the basement, she promptly dropped all her leaves.

Nonetheless, this grow-light was a great buy. Its fake sun makes a laughingstock of winter.  On the darkest, iciest days of January, I can run downstairs and snip some rosemary for dinner. Annuals we once had to repurchase every year now turn their faces toward the grow-light, forgiving its lack of cosmic power, glad just to bask and live.

Photosynthesis is an amazement.

Until this week, that was all I knew. Plants eat light, gulp carbon dioxide, breathe out sweet oxygen. But this thing our plants are doing with the grow light? It is why we even exist.

In Living on Earth, Peter Godfrey-Smith takes us back three billion years to describe how cyanobacteria—or their ancestors—invented their version of photosynthesis. Using energy from the sun, they built organic material, releasing oxygen as they went. “Pulling in carbon dioxide, breaking water molecules apart with the power of light, splicing the elements to build living material, and releasing oxygen gas in tiny puffs,” Godfrey-Smith writes, “they slowly transformed the atmosphere, and the planet along with it, until Earth could power the organic engines of animal life—muscles, nervous systems, brains.”

Us.

First, the oxygen exhaled by the bacteria rusted the earth, turning soil and rock red. Then it started hanging around as a gas. Algae grew, engulfing the bacteria, and formed colonies that, like tiny factories, grew more and more green stuff. First came shy mosses, lingering near streams and ponds; then soft ferns in the shade of caves. Evolution got fancy, making conifers, scratchy grasses, tall pale birch trees and aspens, towering oaks and sequoias. Finally, the orchids arrived, trailed by other flowering plants. The rocky red Earth was now covered by a soft green blanket dotted with color. And the transformation was nowhere near done.

In Harvard biologist Andrew Knoll’s estimation, photosynthesis was “the central event in the history of life.” By splitting water into hydrogen and oxygen and pulling electrons from the hydrogen, the sun’s radiation could be transformed into chemical energy, powerful and portable. Thanks to the cyanobacteria, “Earth became infused, crammed, with energy,” Godfrey-Smith writes. Bonds formed between atoms to store that power. Later, with the help of oxygen, it could be released when needed.

Without that power grid, animal life could never have developed.

My non-science-major brain never associated photosynthesis with, say, my standard poodle, or my own weird and complicated self. Photosynthesis was what plants did, and plants were just here to feed us. But the subtle, momentous difference in Godfrey-Smith’s take is his approach to evolution. He shows us organisms not as the passive products of some Darwinian master plan, but as the causes of evolution.

In the long, fabulous show of life’s progression, humans only dashed to their seats at intermission. First, single-celled creatures clumped together, like kids starting junior high. By setting boundaries, these colonies turned into groups of individual animals, just as one hopes teenagers will. A controllable internal skeleton evolved, making creatures who could act upon the world and move through it. Nervous systems grew intricate, allowing symbolic language, tools, artistic expression, and all the other flashes of genius we use to tell ourselves we are special.

We are, after all, made from light. Our bodies even emit light, which is the opposite of photosynthesis. We do not glow with the wattage of a firefly, mind you. Even when pregnant, our light is undetectable to the naked eye (though I cannot help but wonder if this is what people are sensing when they claim to see auras). Japanese scientists Daisuke Kikuchi and Masaki Kobayashi showed this faint bioluminescence a quarter-century ago, pointing out that our light is emitted rhythmically, after metabolic reactions, and our faces glow the brightest.

“A secret shared among cells, too soft for the human eye,” is how the Croatian writer Monique Marani describes this phenomenon. What strikes me is that nothing could be made from light, or give it off, without photosynthesis.

I return to my plant-watering with newfound reverence.

 

Read more by Jeannette Cooperman here.

 

Jeannette Cooperman

Jeannette Cooperman holds a degree in philosophy and a doctorate in American studies. She has won national awards for her investigative journalism, and her essays have twice been cited as Notable in Best American Essays.

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